IMAC
Leopard
VDL 2.5.1
Sibelius 5.2.5

My Sibelius 5.2.5 starting quitting unexpectedly again this
past week, so I contacted Sibelius and this was their
response, in case some of you are having a similar problem:

Trash your Sibelius 5 Playback configuration settings.

Quit Sibelius.

Go to hard_drive/Users/your_user_directory/Library/Application Support/Sibelius Software/Sibelius 5 folder and delete 'Playback Configurations' folder and the 'PlaybackConfig.xml' file.

Now clear the preferences.

Go to Hard_Drive / Users / Your_Username / Library / Prefernces folder.
Drag 'com.sibelius.sibelius5.plist' into the trash.

Now repair the disk permissions.

To repair disk permissions go to the Hard_Drive>Applications>Utilities folder and open Disk Utility. Select your hard drive on the left side of the window and click on 'Repair Disk Permissions' button.

Restart your computer and see if that fixes the problem.

Thanks for sharing your fix Neal!

I'll move this to the ";helpful hints"; board for future reference.